Java Persistence API (JPA) Application

Java  Persistence API (JPA) provides POJO(Plan Old Java Object) standard and object relational mapping (ORM) for data persistence among applications.


JPA Architecture

Creating a simple JPA Application using MySql

Creating a database in MySql

• Create a database StudentDetails in Mysql.

          create database StudentDetails;

Establishing a database connection to NetBeans

In NetBeans under the Services tab, Right click on the database and select New  Connection

  

Java Server Faces (JSF)

Java Server Faces (JSF) is a server side user interface component framework for Java technology based web applications.

JSF is a component oriented and event driven framework for web applications.

Create a simple JSF application in Maven

• Create the maven web application via command prompt eg:- SimpleJSF  and open it in Net beans.

       The file layout of the project is some thing like this.

• Insert the following dependencies to your pom.xml file to include the jsf2.0 libraries

       <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.0.0-b13</version>
            <scope>compile</scope>
       </dependency>


      <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.0.0-b13</version>
            <scope>compile</scope>
       </dependency>

• Create a new JSF file (index.xhtml) in the project. (New---> JSF Page)

• In web.xml include the following tags for servlet mapping and set the welcome page.

       <context-param>

           <param-name>javax.faces.PROJECT_STAGE</param-name>

           <param-value>Development</param-value>

       </context-param>

  

       <servlet>

          <servlet-name>Faces Servlet</servlet-name>

          <servlet-class>javax.faces.webapp.FacesServlet
          </servlet-class>

          <load-on-startup>1</load-on-startup>

       </servlet>

      <servlet-mapping>

           <servlet-name>Faces Servlet</servlet-name>

           <url-pattern>*.xhtml</url-pattern>

      </servlet-mapping>

  

     <welcome-file-list>

          <welcome-file>index.xhtml </welcome-file>

      </welcome-file-list>

• After that create a managedbean (New-->JSFMAnagedBean-->studentManagedBean)

      In JSF 2.0, Java bean that can be accessed from JSF page is called   
      Managed Bean.

  

   The managed bean can be a normal Java bean, which contains the getter        

  and setter methods,business logic or even a backing bean.

• After that you create the following classes

    The Structure of the application is like this:

      Here Student.java is the Java bean class.

• If you want to insert the prime faces in your application. You should insert the following dependency and repository

       <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>3.2</version>
     </dependency>


    <repository>
            <id>prime-repo</id>
            <name>PrimeFaces Maven Repository</name>
            <url>http://repository.primefaces.org</url>
            <layout>default</layout>
    </repository>

MVC Architecture

MVC is an architectural design pattern. 

• Model - business logic.
• View - User Interface
• Controller - handles user input

Why MVC ?

• View is free of any business logic so looks simple and readable.
• Business logic within the model can be reused for more than one views.

Simple example for MVC with JSP

•  A web page for register the student details. 
•  Here Student name, Parent name, Grade, and Address are input 
fields.
•  User can enter these values by clicking "Insert"
•  Here Student name and Grade are mandatory fields.
•  System should validate this fields and show the proper error message.

For this example 

• Create jsp pages for input interface, Error, Success response messages. - view
• Create a java class (Student.java) for a student model - model
• Create a servlet class for redirect a  proper view - controller  

Student Registration page.

When we click "Insert" button after enter all details. 

If we don't enter the Mandatory fields. This error message will display

Mapping a servlet page
Servlets need to be configured ans it needs to be mapped to a URI (URL/URN).
So we have to include the following mapping to the web.xml file.

<servlet>
    <servlet-name>ServletPage</servlet-name>
    <servlet-class>org.ymini.lukshica.controller.ServletPage</servlet-class>
 </servlet>
  
 <servlet-mapping>
    <servlet-name>ServletPage</servlet-name>
    <url-pattern>/Test</url-pattern>
 </servlet-mapping>


Mappings are used by the servlet container to translate a particular request URI to a particular servlet.

Maven Tomcat Plugins

I tried to install and build a war into a tomcat server through 
maven. 
 I add the following tomcat plugin into the pom.xml file 


<plugins> 
        <!-- Maven Tomcat Plugin --> 
        <plugin> 
                <groupId>org.codehaus.mojo</groupId> 
                <artifactId>tomcat-maven-plugin</artifactId> 
                        <configuration> 
                                <server>TomcatServer</server> 
                        </configuration> 
        </plugin> 
</plugins>

My First Project in Maven

Steps to build and execute a maven project

·    Install jdk 1.7 and set the class path

·     Install 3.0.4 and set the class path -http://maven.apache.org/download.html#Installation

·    Type “mvn –version” in the command prompt to check whether the maven installed properly or not.

 ·   Create a directory to build your project and go that directory via command prompt

       C:\users\Lukshy\Project>

 ·   Type “ mvn archetype:generate -DarchetypeArtifactId=maven-archetype-webapp -DgroupId=org.yarlithub.yschool -DartifactId=yschool” in the command prompt. 

       · Then a directory yschool (project name) has created in that folder. Go to that directory and compile the project.

      Type “mvn compile” 

      C:\users\Lukshy\Project\yschool> mvn compile

 ·  Here also the build success message displayed
 ·  Include the jetty plugin in the pom.xml file

      · Type "mvn install jetty : run” . Now the jetty will be start.

 · Now we can see the page in the browser.Go to the browser and type:   

      http://localhost:8080/yschool

·    Go to the file index.jsp along this path yschool -->src --> main --> webapp -->index.jsp and we can we can edit it. 

Session 1 - Java web programming

This session was conducted by JK. First he talked about why they started ySchool project and what they going to do with this course.From this course I hope that we can get the ability to develop an open source project.

What I learned

What is web programming?

Web programming is about interaction between the computers via browser.JSP and Servlets are Java’s web technologies.

Web Server – The webserver contains the all web data. When a client requests a web object it gives the correct object to the client.

Eg: - Apache Server         

ISS

Servlet Container – It is also a webserver. It is most specific to dynamic data.When we write java related applications the apache server doesn’t accept them.  Therefore we need a servlet.  Servlet can process JSP.

Application Server - Application server also a server which exposes business logic to client applications through various protocols.

Process - when a client request a simple web page

• The client request a simple hello.jsp file to the server

• The server contains the jsp container. Which is used for process JSP pages

• The container knows which servlet controller is appropriate to process this page and send to it.

• Then the servlet page is generated.

• The page is send back to the container as a servlet class file with a response message.

• The container execute it and send the response to the client.

MVC - Model View Controller
MVC is a way of splitting an application in to three parts: a model, a view and a controller.
Nowadays we have to satisfy multiple type of end users. There fore we need a Model View Controller to support different type of users.
In web applications 
JSP pages are the views and the servlets are as controllers.

  

ySchool Project

I have a great opportunity to participate at the free crash course on Java web programming. This free online course is held by yarlIt hub community for developing ySchool project.

As a Jaffna student I would like to say, joining on yschool project is a good chance to us. Because we haven’t got any opportunity like this yet